Operation PrincipleThe Arthur Activated Sludge Respirometer is available with single or dual test chambers within a waterbath tank. Each measuringdevice utilzes a combination of sample chamber, carbon dioxidescrubber, sensitive gas volume transducer, air reservoir and foamtrap, air pump and automatic gas exchange system.† The latterfour are located in separate sealed compartments that can beeasily disconnected and replaced if necessary.† The air pumpprovides continuous air circulation through the sample chamberand the scrubber.The entire air system is closed to the atmosphere.As the specimen in the chamber utilzes oxygen and generatescarbon dioxide, the carbon dioxide is immediately removed by thecaustic solution in the scrubber.† The volume of carbon dioxide produced is therefore not present to balance the volume of oxygenutilized, and there is a net loss of gas volume equal to the volumeof oxygen utilized.† The change of gas volume is sensed by the gasvolume tranducer.† The transducer converts the volume of oxygenused to an electrical signal which is fed to a computer.† Theinstrument produces a continuous graphical record of respiration.It can also be used to measure volume of gas produced, as inanaerobic processes.

Sample Chamber...The instrument is normally furnished with a two-liter
cylindrical chamber, but various sizes†
and shapes are available.On the
removable top of the Sample Chamber is a fill tube closed with a threaded
plug.† The plug is fitted with a syringe
connector for calibration.† Sample Chambers can be removed and
disassembled to clean.† When installed, each
Sample Chamber is connected to a valved drain.†
With liquid samples the chamber utilizes an airlift pump to aerate and
mix the sample.† Air is distributed at
the base of the airlift column through a fine bubble diffuser.† Solid samples are usually placed on a porous
stage and the air flows up through the stage.

Respirometer Module...This rectangular shaped module is located behind the Sample Chamber and CO2 Scrubber Chamber in the waterbath. It consists of an assembly frame with volumetric transducer box attached, an air reservoir and foam trap, an automatic gas exchange system box and an air pump box.† The air reservoir and foam trap, gas exchange system box and the air pump box can be easily removed from the assembly frame.† A drain is provided to remove the oil from the volumetric transducer.

Water Bath.... Respiration tests can be performed at a full range
of temperatures using the waterbath.† The
water in the bath completely covers the respirometer module, sample chamber and
CO2 Scrubber.† Temperature control can be obtained by using
an Immersion Heater in the waterbath. Cooling can be provided with an Immersion
Chiller.†

The Electronics Module...All controls to operate the respirometer are contained in
the electronics module.† This includes a
power switch with indicating light, on-off switches for atmospheric pressure
compensation, automtic venting and zero and span adjustment controls.

CALIBRATION

The respirometer is
calibrated by withdrawing a prescribed amount of air with a calibrated syringe.